Wafer carrier having thermal uniformity-enhancing features

A wafer carrier assembly for use in a system for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), the wafer carrier assembly comprising:

• a wafer carrier body formed symmetrically about a central axis, and including a generally planar top surface that is situated perpendicularly to the central axis and a planar bottom surface that is parallel to the top surface;
• at least one wafer retention pocket recessed in the wafer carrier body from the top surface, each of the at least one wafer retention pocket including a floor surface and a peripheral wall surface that surrounds the floor surface and defines a periphery of that wafer retention pocket, the wafer retention pocket being adapted to retain a wafer within the periphery when subjected to rotation about the central axis;
• at least one thermal control feature that includes an interior cavity formed in the wafer carrier body and defined by interior surfaces of the wafer carrier body, the interior cavity being enclosed by at the bottom surface and at least one of the top surface and the floor surface;
• wherein the at least one thermal control feature has a lower thermal conductivity than the wafer body.

Apparatus for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), comprising:

• a reaction chamber;
• a rotatable spindle having an upper end disposed inside the reaction chamber;
• a wafer carrier for transporting and providing a support for the one or more wafers, the wafer carrier being centrally and detachably mounted on the upper end of the spindle and being in contact therewith at least in the course of a CVD process;
• and
• a radiant heating element disposed under the wafer carrier for heating thereof;
• wherein the wafer carrier comprises
• a wafer carrier body formed symmetrically about a central axis, and including a generally planar top surface that is situated perpendicularly to the central axis and a planar bottom surface that is parallel to the top surface;
• at least one wafer retention pocket recessed in the wafer carrier body from the top surface, each of the at least one wafer retention pocket including a floor surface and a peripheral wall surface that surrounds the floor surface and defines a periphery of that wafer retention pocket, the wafer retention pocket being adapted to retain a wafer within the periphery when subjected to rotation about the central axis;
• at least one thermal control feature that includes an interior cavity formed in the wafer carrier body and defined by interior surfaces of the wafer carrier body, the interior cavity being enclosed by at the bottom surface and at least one of the top surface and the floor surface;
• wherein the at least one thermal control feature has a lower thermal conductivity than the wafer body such that heat flow in the wafer carrier body caused by operation of the radiant heating element tends to concentrate in regions other than the regions above the at least one thermal control feature.

A method for assembling a wafer carrier for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), the method comprising:

• forming a wafer carrier body symmetrically about a central axis, including forming a generally planar top surface that is situated perpendicularly to the central axis and forming a planar bottom surface that is parallel to the top surface;
• forming at least one wafer retention pocket recessed in the wafer carrier body from the top surface, each of the at least one wafer retention pocket including a floor surface and a peripheral wall surface that surrounds the floor surface and defines a periphery of that wafer retention pocket, the wafer retention pocket being adapted to retain a wafer within the periphery when subjected to rotation about the central axis;
• situating a thermally-insulating spacer at least partially in the at least one wafer retention pocket to maintain a spacing between the peripheral wall surface and the wafer, the spacer being constructed from a material having a thermal conductivity less than a thermal conductivity of the wafer carrier body such that the spacer limits heat conduction from portions of the wafer carrier body to the wafer;
• and
• forming a spacer retention feature in the wafer carrier body such that the spacer retention feature engages with the spacer and provides a surface oriented to prevent centrifugal movement of the spacer when subjected to rotation about the central axis.